For the uplink of future broadband systems, single-carrier based approaches with orthogonal frequency division are of interest. These approaches, particularly Interleaved Frequency Division Multiple Access (IFDMA) and its frequency-domain related variant known as DFT-Spread-OFDM (DFT-SOFDM), are attractive because of their low peak-to-average power ratio (PAPR), frequency domain orthogonality among users, and low-complexity frequency domain equalization.
Out of band emissions require de-rating of the maximum transmit power levels of wireless terminals to meet adjacent channel leakage ratio (ACLR) requirements, depending on the occupied bandwidth of the assigned channel and its location in the carrier band. Also, coverage for uplink control signaling such as ACK/NACK, CQI, and scheduling requests is limited when the assigned time-frequency resource is distributed mainly in the time domain (time division multiplexing) compared to a distribution in the frequency domain (frequency division multiplexing). DFT-SOFDM has thus emerged as a candidate for the Long Term Evolution of the 3rd Generation Partnership Project (3GPP) wireless communication protocol, also known as Evolved Universal Terrestrial Radio Access (E-UTRA).
The various aspects, features and advantages of the disclosure will become more fully apparent to those having ordinary skill in the art upon careful consideration of the following Detailed Description thereof with the accompanying drawings described below. The drawings may have been simplified for clarity and are not necessarily drawn to scale.